1. Field of Invention
This invention relates to portable ladders, and to stabilizing means thereof.
2. Prior Art
Portable ladders are so unstable in use that the assistance of a second person is often advisable for steadying them. A stabilizing apparatus would be of interest to many ladder owners, but only if it were convenient and inexpensive. Safety devices of this nature must be nearly trivial to use, or they will be underutilized. A well-known example is the automobile seat belt, the utilization of which has been improved via automatic adjustment and deployment features. This suggests that, to be practical, a ladder stabilizer must be very convenient and unobstrusive, and not require adjustment on each deployment.
An improvement in portable ladders is the availablility of reconfigurable scaffold/ladder devices. These can be configured as a step ladder, straight ladder, or scaffold. However, other than providing the most appropriate ladder type for the job, they do not solve the stability problem, and they have disadvantages: they are more complicated to use than plain ladders, requiring learning of the reconfiguration operations; and they waste an investment in existing ladders, since they replace, rather than enhance existing equipment.
A stabilizer bar has been reported which attaches to the rails of a ladder, but it appears to require adjustment or reattachment for each use, and adjustment or removal for each movement of the ladder and for transport and storage, thus it lacks convenience. Also it exerts leveraged stress at a single position on each rail. This concentration of stress may restrict its safe use to ladders with exceptionally strong rails, stronger than those on most aluminum ladders.